Submission #892734

#	Time	Username	Problem	Language	Result	Execution time	Memory
892734		tvladm2009	Building Bridges (CEOI17_building)	C++17	30 / 100	17 ms	2836 KiB

building

#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()

const ll INF = 1e18;

struct Line {
    ll a;
    int b;
    
    ll eval(int x) {
        return a * x + b;
    }
};

namespace LiChao {
    struct Node {
        Line val;
        Node* left;
        Node* right;
        Node(Line val_ = {0, 0}) {
            val = val_;
            left = right = NULL;
        }
    };
    void update(Node* &root, int from, int to, Line val) {
        if (root == NULL) {
            root = new Node(val);
        } else {
            int mid = (from + to) / 2;
            if (val.eval(mid) < root->val.eval(mid)) {
                swap(val, root->val);
            } 
            if (val.eval(from) < root->val.eval(from)) {
                update(root->left, from, mid, val);
            }
            if (val.eval(to) < root->val.eval(to)) {
                update(root->right, mid + 1, to, val);
            }
        }
    }
    ll query(Node* root, int from, int to, int x) {
        if (root == NULL) {
            return INF;
        } else {
            int mid = (from + to) / 2;
            if (x <= mid) {
                return min(query(root->left, from, mid, x), root->val.eval(x));
            } else {
                return min(query(root->right, mid + 1, to, x), root->val.eval(x));
            }
        }
    }
}

int32_t main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin >> n;
    vector<int> h(n + 1), w(n + 1);
    for (int i = 1; i <= n; i += 1) {
        cin >> h[i];
    }
    vector<ll> pref(n + 1, 0);
    for (int i = 1; i <= n; i += 1) {
        cin >> w[i];
        pref[i] = pref[i - 1] + w[i];
    }
    vector<ll> dp(n + 1, INF);
    LiChao::Node* root = NULL;
    dp[1] = 0;
    for (int i = 1; i <= n; i += 1) {
        if (i != 1) {
            dp[i] = LiChao::query(root, 1, 1e6, h[i]);
            dp[i] += pref[i - 1] + h[i] * h[i];
        }
        int a = -2 * h[i];
        int b = dp[i] + h[i] * h[i] - pref[i];
        LiChao::update(root, 1, 1e6, {a, b});
    }
    cout << dp[n] << endl;
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40